1. Field of the Invention
The present invention generally relates to an exhaust gas cleaning apparatus for an internal combustion engine. More specifically, the present invention relates to an exhaust gas cleaning apparatus that removes exhaust gas particulate matter captured in an exhaust gas particulate filter arranged in a downstream position by oxidizing the particulate matter using nitrogen dioxide (NO2) generated by an oxidation catalytic converter arranged in an upstream position.
2. Background Information
There are various known technologies for cleaning exhaust gas discharged from an engine. For example, Japanese Laid-Open Patent Publication No. 2005-315190 discloses a known exhaust gas cleaning apparatus for a diesel engine. Here, the exhaust gas cleaning apparatus is a continuously regenerating apparatus having an exhaust gas particulate filter that captures exhaust gas particulate matter and an oxidation catalytic converter arranged upstream of the exhaust gas particulate filter. While the engine is running, the apparatus continuously removes exhaust gas particulate matter captured in the exhaust gas particulate filter by oxidizing the particulate matter with nitrogen dioxide generated by the oxidation catalytic converter. The nitrogen dioxide serves as a highly active oxidizing agent.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved internal combustion engine exhaust gas cleaning apparatus. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.